COVID-19 vaccine effectiveness against severe COVID-19 requiring oxygen therapy, invasive mechanical ventilation, and death in Japan: A multicenter case-control study (MOTIVATE study).

INTRODUCTION: Since the SARS-CoV-2 Omicron variant became dominant, assessing COVID-19 vaccine effectiveness (VE) against severe disease using hospitalization as an outcome became more challenging due to incidental infections via admission screening and variable admission criteria, resulting in a wide range of estimates. To address this, the World Health Organization (WHO) guidance recommends the use of outcomes that are more specific to severe pneumonia such as oxygen use and mechanical ventilation. METHODS: A case-control study was conducted in 24 hospitals in Japan for the Delta-dominant period (August-November 2021; "Delta") and early Omicron (BA.1/BA.2)-dominant period (January-June 2022; "Omicron"). Detailed chart review/interviews were conducted in January-May 2023. VE was measured using various outcomes including disease requiring oxygen therapy, disease requiring invasive mechanical ventilation (IMV), death, outcome restricting to "true" severe COVID-19 (where oxygen requirement is due to COVID-19 rather than another condition(s)), and progression from oxygen use to IMV or death among COVID-19 patients. RESULTS: The analysis included 2125 individuals with respiratory failure (1608 cases [75.7%]; 99.2% of vaccinees received mRNA vaccines). During Delta, 2 doses provided high protection for up to 6 months (oxygen requirement: 95.2% [95% CI:88.7-98.0%] [restricted to "true" severe COVID-19: 95.5% {89.3-98.1%}]; IMV: 99.6% [97.3-99.9%]; fatal: 98.6% [92.3-99.7%]). During Omicron, 3 doses provided high protection for up to 6 months (oxygen requirement: 85.5% [68.8-93.3%] ["true" severe COVID-19: 88.1% {73.6-94.7%}]; IMV: 97.9% [85.9-99.7%]; fatal: 99.6% [95.2-99.97]). There was a trend towards higher VE for more severe and specific outcomes. CONCLUSION: Multiple outcomes pointed towards high protection of 2 doses during Delta and 3 doses during Omicron. These results demonstrate the importance of using severe and specific outcomes to accurately measure VE against severe COVID-19, as recommended in WHO guidance in settings of intense transmission as seen during Omicron

Magnetic Resonance Imaging of the Normal Tongue: Qualitative Evaluation of Fat-suppressed Contrast Enhanced Images

Objective: For diagnosing the lesions on magnetic resonance imaging (MRI), it is necessary to understand normal structures on each sequence. In this study, we attempted to clarify structures of the normal tongue on fat -suppressed enhanced MRI qualitatively. Clinical material and method: Twenty-seven fat-suppressed enhanced MR images of normal tongue were studied, which were obtained using a T1 weighted spin echo pulse sequence (T1WI- E) with the chemical shift selective (CHESS) method by a superconducting MRI scanner operating at 1.5T. Tongue structures and their signal intensities on fat-suppressed enhanced images were assessed and compared to those obtained by non-enhanced T1WI. Results: Normal tongues were found to be composed of a symmetrical high signal area (HSA), low signal area (LSA), lingual septum, bilateral sublingual gland, and genioglossus muscle on non- enhanced T1WI. In the fat-suppressed enhanced images, HSA and lingual septum signal intensities were suppressed. Further, though the lingual mucosa was well visualized in fat-suppressed enhanced images (P<0.05), differentiation of HSA and LSA was difficult as compared to the non- enhanced scans (P<0.05). Conclusion: Fat-suppressed enhanced scans demonstrated simple anatomical structures as com- pared to conventional T1WI with independent signal intensity. Accordingly, we conclude that it is necessary to use both sequence for diagnosing the mass lesion located in the tongue